Half to victor sohlbsinger



(80 Model.) Q

A; PRUSKER.

' POLYGONPROTRAGTOR. V 0 2 No. 257,832. Patented May 9, 1882.

Wiirzeaded. Zia/fish)" g &Z%M M00 N. PEIERS. PIMo-Ulhomphur. Wash ngton. 0.1:.

" UNITED STATES P TENT Grates.

ARTHUR PRIISKER, OF VIENNA, AUSTRIA-HUNGARY, ASSIGNOR OF ONE- HALF '-TO VICTOR SGHLESINGER, OF SAME PLACE.

PO-LYG'ON-PROTRACTO R.

SPECIFICATION forming part of Letters Patent No. 257,832, dated May 9, 1882.

Application filed September 24, 188i. (No model.) Patented in Austria February 512, 1880, in Hungary February 22, 1880, in

. France July 10, 1880, and in Germany August 30, 1880.

To all whom it may concern Be it known that I, ARTHUR PRiisKER, a subject of the Emperor of Austria-Hungary, residing at Vienna, in the Empire of Austria- Hungary, have invented certain new and usefulImprovementsinPolygon-Protractors and I do hereby declare the following to be a full,

clear, and exact description of the invention,

such as will enable others skilled in the art to which it appertains to make and use the same,

reference being had to the accompanying drawi n g, and to letters or figures of reference marked thereon, which form a part of this specification.

The object of this invention is to provide a device for facilitating the construction of polygons or for dividing circles into any number of parts. The device consists essentially of a disk made of a perforable material-such as leather, paper, card-board, or other analogous material. Said disk has an annular central opening, and its face isprovided with a series of concentric circles, each divided into a different number of equal parts, one of such' cirz5'cles being divided into degrees. The number of the divisions is indicated by corresponding figures placed between the circles. The space between the two smallest or inner concentric circles is divided into four equal parts corre- 0 spending to the vertical and horizontal diameters of said circles.

If it is desired to construct a given polygon within a circle drawn, or if it is desired to divide said circle into a given number of equal 5 parts, the prot'ractor is laid upon the circle to be divided, or within which the polygon is to be constructed, in such manner that the qua-rter divisions of the inner circles on the protractor will exactly coincide with the like di- 0 visions of the horizontal and vertical diameters of the drawn circle. Then, by means of a needle or analogous instrument, puncture the points of division of that circle on the protractor that has the desired number of equal parts, remove the protractor, and draw lines intersecting the center of the drawn circle and the punctures, when said circle will be divided into the desired number of equal parts.

Should it be necessary'to divide a circle into each of fifteen degrees.

a number of equal parts not indicated by the protractor, these may be obtained by using the alternate points of division on one of the circles on the protractor or by dividing the relative are. For instance, an octagon may be constructed within a given circle by using that circle on the protractor that is divided into sixteen equal parts and puncturing everyother point of division, whereby the circle drawn will be divided into eight equal parts. If, on the other hand, it is desired to divide a circle into fifty-four equal parts, that circle on the protractor which is divided into twenty-seven equal parts may be taken, and each of these divisions may then be divided into two equal parts, and so on.

That my invention may be better understood, I will describe the same in detail, reference being had to the accompanying drawing,which represents the polygon-protractor constructed according to my invention.

A is a disk; a, its central circular aperture; 1), its outer periphery. As shown, said disk has upon its surface seventeen concentric circles, the space between each two of them being divided into a different number of equal parts. The space betweenthe inner periphery and the first circle is divided in Your equal parts, the lines of division 0 c c c forming fragments of two diameters at right angles to each other. The space between the second and third circle is divided into twenty-four equal parts, The next space is di vided into sixteen equal parts, the next into seventeen equalparts, and so on, the outer circle being divided into thirty equal parts.

It will be understood that any other system of division may be adopted, and that the number of circles may be increased or diminished.

What I claim is l. The herein-described polygon-protractor, consisting of a disk constructed of material capable of being perforated, and provided with a central aperture, a series of concentric circles, each divided into a. given number of equal parts, and radial indices indicating the subdivisions of said circles, substantially as and for the purpose specified.

2. The herein-described polygon-protractor,

consisting of a disk constructed of a material" In testimony whereof I affix my signature in capable of being perforated, and provided with presence of two witnesses.

a central aperture, a circle divided into de- 1 grees, a series of auxiliary circles, each di- ARTHUR PRUSKER. vided into a given number of equal parts, and

radial indices indicating the subdivisions of Witnesses:

said circles, substantially as and for the pur- VICTOR KARMIN, Engineer.

poses specified. HANS KOTTASH. 

